The subject invention relates to an aircraft warning system for alerting the flight crew in the flight deck compartment of an aircraft that a troublesome situation is occurring in the passenger cabin, and, more specifically, to a flight attendant actuated warning system that can be actuated by a flight attendant in the passenger cabin without detection for alerting the flight crew in the flight deck compartment that a potential hijacking, passenger initiated disturbance, or other troublesome situation is occurring in the passenger cabin.
Presently, the flight attendant or attendants on a commercial airliner have two ways of contacting the flight crew in the flight deck compartment of the commercial airliner. The flight attendant may contact the flight crew in the flight deck compartment by calling one of the pilots over the interphone or by knocking on the compartment door. The interphone is an internal intercom system of the aircraft that is very much like those used in offices. On a regional airliner, an interphone is located in the front of the passenger cabin in view of at least some of the passengers and is also used by the flight attendant to make passenger announcements. On a regional airliner, there may be no interphone in the rear of the passenger cabin. On a larger commercial airliner, due to the length of the passenger cabin, there may be interphones at both the front and the rear of the passenger cabin. To contact one of the pilots in the flight deck compartment, a flight attendant picks up the handset of the interphone system and pushes a call button. The call button sounds a chime in the cockpit letting the flight crew in the flight deck compartment know that a flight attendant would like to talk with them. After hearing the chime, one of the pilots turns the intercom on and communicates with the flight attendant. Under normal circumstances, communication between the flight attendant(s) and the flight crew on the flight deck through the interphone system works quite well. However, in an emergency, such as a potential hijacking, a passenger initiated disturbance or other troublesome situation, this method of communication presents several serious problems. At least some of the passengers in the passenger cabin can see and/or hear a flight attendant calling the flight crew in the flight deck compartment over the intercom system and where the potential hijackers or the disruptive passenger(s) can see and/or hear a flight attendant making the call, the potential hijacker(s) or disruptive passenger(s) might be spurred into action by the attendant""s attempt to make the call thereby further endangering the flight attendant, the other members of the flight crew, and innocent passengers. Getting to the interphone handset can also be a problem or impossible for the flight attendant, perhaps the flight attendant""s path to the interphone handset or handsets is blocked by the potential hijacker(s) or disruptive passenger(s) and the flight crew in the flight deck compartment never receives a warning or alert. In a situation such as a potential hijacking where time is of the essence, there may not be time for the attendant to get to a handset of the interphone system and deliver a message to the flight crew on the flight deck. Of course, where a flight attendant must move to the front of the passenger cabin and knock on the door of the flight deck compartment to gain the attention of the flight crew on the flight deck, the situation can only become worse. Extra time would be consumed by the need for one of the pilots to get out of his/her seat, look through the peephole, and open the flight deck door to communicate with the flight attendant. In addition, if one of the pilots unlocks and opens the flight deck door to talk to the flight attendant, this would provide access to the flight deck compartment and that, especially in a potential hijacking situation, could be extremely dangerous for both the flight crew and passengers.
Accordingly, for years there has been and, in view of Sep. 11, 2001, there still is a need for immediate and undetected communication from a flight attendant to a flight crew in the flight deck compartment of the aircraft to alert the flight crew on the flight deck that a potential hijacking, a passenger initiated disturbance or some other troublesome situation or emergency is occurring in the passenger cabin. Such an undetected alert will not further endanger the flight attendant by drawing attention to the fact that the flight attendant is in contact with the flight crew on the flight deck and will enable the flight crew in the flight deck compartment to initiate an appropriate response to the situation. Where there is a potential hijacking, the flight crew in the flight deck compartment will not be blind-sided by the hijackers and can go into a defensive posture taking whatever steps considered appropriate. For example, the flight crew could get ready to deny the hijackers access to the flight deck compartment through the flight deck door; the situation could be communicated to air traffic controllers, the military and other appropriate authorities by the pilot; and/or the pilot could divert to a near by airport, land and thereby prevent the aircraft from being used by the terrorists as they did on September 11th. With the military alerted the military could stand by and be ready to react to the situation as it unfolds and ensure that the aircraft is not flown into a building or other facility, such as but not limited to an office building, a military installation, a nuclear power plant, athletic stadium, dam, etc.
The flight attendant actuated warning system and method of the subject invention provides a unique system and method for an immediate and undetected communication from a flight attendant to a flight crew in the flight deck compartment of the aircraft to alert the flight crew on the flight deck that a troublesome situation such as a potential hijacking, a passenger initiated disturbance, or some other troublesome situation or emergency is occurring in the passenger cabin.
The flight attendant actuated warning system of the subject invention includes a receiver unit and one or more portable transmitter units. The receiver unit is located in the flight deck compartment of an aircraft to alert the flight crew on the flight deck of the aircraft in the event a troublesome situation develops in the passenger cabin and at least one and preferably each flight attendant in the passenger cabin of the aircraft carries a portable transmitter unit that can be easily concealed from the passengers in the passenger cabin. Each portable transmitter unit can be actuated by the flight attendant carrying the unit, without detection by the passengers in the passenger cabin, to transmit a preselected activation signal to the receiver unit in the flight deck compartment. To avoid interfering with the function of the avionic and navigational equipment of the aircraft, the preselected signal or signals transmitted by each portable transmitter unit are transmitted at a frequency or frequencies outside a frequency range utilized by the avionic and navigational equipment of the aircraft. When the receiver unit in the flight deck compartment receives a preselected activation signal from a portable transmitter unit located in the passenger cabin of the aircraft (preferably the signal must be transmitted for a preselected activation period of 1 or 2 seconds to minimize false alarms), the receiver unit is activated to audibly and visually alert the flight crew in the flight deck compartment that a troublesome situation is occurring in the passenger cabin of the aircraft.
Preferably, each portable transmitter unit can transmit two or more preselected activation signals and the receiver unit can receive and process the two or more preselected activation signals from each portable transmitter unit of the system. In one embodiment of the subject invention, each portable transmitter unit of the system can transmit two preselected signals and the receiver unit can receive and process the two preselected signals from each portable transmitter unit. The first preselected activation signal transmitted by each transmitter unit is processed by the receiver unit to alert the flight crew in the flight deck compartment that a first troublesome situation is occurring in the passenger cabin, such as but not limited to a potential hijacking. The second preselected activation signal transmitted by each portable transmitter unit is processed by the receiver unit to alert the flight crew in the flight deck compartment that some other troublesome situation is occurring in the passenger cabin, such as but not limited to a confrontation between a flight attendant and a disruptive passenger or air rage.
However, the flight attendant actuated warning system of the subject invention may use portable transmitter units that each transmit three or more preselected activation signals and a receiver unit that can receive and process the three or more preselected activation signals from each portable transmitter unit of the system. Such a system, rather than having only two categories of alert, such as a hijacking alert and a troublesome situation alert other than a hijacking alert, could have a series of alerts, e.g. a level one alert, a level two alert, a level three alert etc., reflecting the seriousness of the situation in the passenger cabin.
Preferably, after the audio and visual alarms of the receiver unit have been activated for a preselected alarm period (e.g. 13 to 15 seconds) through the receipt by the receiver unit of a preselected activation signal from a flight attendant, the receiver unit automatically deactivates the audio and visual alarms and returns the receiver unit to a standby condition so that the receiver unit can again be activated by the future receipt of a preselected activation signal. The receiver unit also includes a manual reset device that may be actuated by one of the members of the flight crew in the flight deck compartment to deactivate the audio and visual alarms before the end of the preselected alarm period and return the receiver unit to a standby state so that the receiver unit is again ready to receive a preselected activation signal from a flight attendant.
In a preferred embodiment of the subject invention, the receiver unit also includes a radio transmitter that transmits on the international emergency frequency or whatever frequency designated by the FAA (Federal Aviation Administration) and/or FCC (Federal Communication Commission). Air traffic controllers and the military continuously monitor the international emergency frequency and by transmitting over this international emergency frequency, the radio transmitter of the receiver unit will not interfere with the air traffic control frequency being used by the aircraft and other aircraft. The radio transmitter can be programmed to automatically transmit the call sign and flight number of the aircraft when the radio transmitter is operating and preferably, includes a microphone for automatically picking up and transmitting voices and other sounds in the flight deck compartment when the radio transmitter is operating. Once the receiver unit has been activated by the receipt of a preselected activation signal that indicates a potential hijacking, if the flight crew does not deactivate and return the receiver unit to a standby state through operation of the manual reset device prior to the expiration of a preselected time period (e.g. such as but not limited to a time which may coincide with but is typically longer than the activation period of the audio and visual alarms), the receiver unit automatically turns on the radio transmitter which begins transmissions on the international or other designated emergency frequency and changes the squawk code of the aircraft""s ATC transponder (Air Traffic Control transponder) to the international hijacking code so that air traffic control and the military can identify and track the aircraft on the radar screen that is being hijacked. Once the radio transmitter is turned on and the code transmitted by the aircraft""s ATC transponder is changed to the hijacking code, unless the receiver unit is reset using the manual reset switch, the radio transmitter remains on to transmit the aircraft""s call sign and the flight number and voices and sounds from the flight deck compartment and the transponder continues to squawk the hijacking code. Preferably, the call sign and flight number are only transmitted for a short period of time so that voices and noises from the flight deck can be better monitored by air traffic control and the military. Thus, with the radio transmitter turned on and transmitting, the air traffic control and the military can monitor what is happening in the flight deck compartment of the aircraft during an attempted hijacking and/or flight deck compartment invasion. Furthermore, since the audio and visual alarms of the receiver unit have been deactivated at the end of the preselected alarm period, a hijacker""s attention will not be drawn to the receiver unit and the hijacker(s) will be unaware that their activities in the flight deck compartment are being monitored by the air traffic controllers and the military.
In a preferred embodiment of the subject invention, the flight attendant actuated warning system also includes one or more portable receiver units that may be carried by each flight attendant where there are two or more attendants and any federal air marshal present in the passenger cabin. The receipt by the portable receiver unit of a preselected activation signal from a portable transmitter unit in the passenger cabin for the preselected activation period actuates an alarm to alert other flight attendants and any federal air marshal present that a flight attendant is involved in a potential hijacking or other troublesome situation. Preferably, the portable receiver unit alarm is a silent alarm, e.g. a vibrating device, so that attention will not be drawn to any flight attendant or federal air marshal, a federal air marshal""s presence will remain undetected, and the passengers in the passenger cabin will not be aware that an alert has been initiated. The silent alarm will automatically turn off and the portable receiver will automatically be reset to a standby mode after a preselected time period and/or the portable receiver will be provided with a manual reset device to return the portable receiver to a standby mode.